This invention relates to a two piece plastic fastener. More particularly, the invention relates to a plastic rivet of the type having an expandable portion and a drive pin molded as a single piece. This type of plastic rivet has a drive pin molded to a frangible member over a hole in fastener's head. After insertion of an expandable prong and a portion of the body of the rivet in a hole provided in the members to be fastened together, the drive pin is driven into the body to break the frangible member. Converging tapered surfaces on the prongs are engaged by the drive pin which causes the prong to expand apart. Retention means between the drive pin and prongs holds the drive pin in place with the prongs expanded against the backside of the part.
It is desirable in such a rivet that the drive pin be predriven after molding of the part to an intermediate position within the body of the rivet whereat the prongs are not yet expanded. Means for retaining the drive pin in the predriven position must be provided for.